SCS2: Supply and industry chain of critical minerals for low-carbon and clean energy development (1)

China's nickel ore import supply chain faces escalating risks from global resource competition and geopolitical instability, threatening the new energy and stainless steel industries. This study develops a four-dimensional risk assessment framework comprising availability, acceptability, accessibility, and controllability, quantified using entropy-weighted TOPSIS to construct a risk index. A multi-model early warning system incorporating GRU, LSTM, and MLP is established, with MLP achieving optimal performance (RMSE=1.035, MAE=0.875, R2=0.94) in capturing nonlinear and volatile risk patterns. SHAP interpretability analysis identifies inventory levels, transportation risk, and import concentration as the top drivers of risk fluctuations, followed by electric vehicle demand growth and geopolitical tensions. An MLP-based inversion model enables spatio-temporal trade-inventory optimization, reducing the risk index to 31.1, the lowest value across all policy scenarios. The findings strengthen critical mineral supply security and provide a transferable risk modeling framework for complex global uncertainties.

This study systematically decomposes the dynamic transmission pathways of geopolitical risks on copper supply chain pricing mechanisms using a Time-Varying Parameter Local Projection (TVP-LP) regression model, based on global daily data from January 2023, to December 2025. The empirical results reveal that geopolitical risks exert whole-chain shock effects on the copper supply chain, yet their impact intensity varies across four segments: upstream mining extraction, midstream smelting and processing, downstream end-use applications, and recycled resource recovery. This differentiated impact underscores the high sensitivity of global copper markets to geopolitical disturbances. Furthermore, geopolitical actions trigger stronger price fluctuations than geopolitical threats. Additional analysis indicates that medium- to long-term geopolitical risk shocks have more pronounced effects on both upstream and downstream segments, while long-term shocks demonstrate more persistent and significant impacts on upstream activities, highlighting the upstream sector as the core node for geopolitical risk transmission. This study enhances understanding of the dynamic asymmetric transmission mechanisms of geopolitical risks on copper supply chain pricing and provides quantitative evidence for global copper market participants to formulate differentiated risk mitigation strategies.

This study investigates the interconnectedness and quantile causality by integrating the China biodiversity index, energy market, and commodity market through a Biodiversity-Energy-Commodity Framework. Constructing a composite analytical framework integrating QVAR, wavelet coherence, and quantile causality analysis to reveal the risk transmission pathways between biodiversity and commodities across multiple dimensions, including the time-frequency domain, bear-bull and normal market conditions, and state dynamics. We find significant variations in the total connectedness index under different market conditions. In the beer and bull market, total connectedness is higher than normal market total connectedness. The results reveal the asymmetric risk transmission of the biodiversity index between the energy and commodity markets under extreme market conditions. During extreme downturns, exchange rates play a central role in the impact of shocks, showing significant sensitivity to shocks to rubber, steel, and non-ferrous metals. Under normal conditions, different markets exhibit a high degree of independence. During extreme upturns, net risk inflows into biodiversity intensify. Wavelet coherency findings demonstrated that Biodiversity substantially affected market performance of commodity markets, exhibiting variable impacts across temporal periods, frequency characteristics, and market condition states. Quantile causality test findings indicate the strongest causality at the mid-quantile, implying that BIO affects the mid-level most, with decreasing impact at the lower and higher levels. These findings provide new insights into different markets' connection spillover effects and highlight the protection of biodiversity from a different market's perspective in supporting the Convention on Biological Diversity.